1. Field of the Invention
The present invention relates to novel compounds. More particularly it is concerned with 12-alkyl-1,4,7,10-tetraazacyclotridecane which can be used in selectively and efficiently capturing metal ions, for example, metal ions contained in waste water.
2. Description of the Prior Art
Metal ions such as copper, cobalt, nickel, mercury, cadmium, zinc and the like ions contained in waste water have hitherto been removed from the standpoint of preventing pollution. Metal ion capturing agents for use in removing these metal ions include activated carbon, kieselguhr, and the like, which capture the metal ions by physical absorption, and ion exchange resins, chelate resins, and the like, which capture the metal ions by chemical binding action. These metal ion capturing agents, however, are of no practical value since activated carbon, kieselguhr, and the like are insufficient in removing low concentrations of the metal ions, and ion exchange resins are of low selectivity to the metal ions. With regard to chelate resins, since they are of high selectivity to all the heavy metal ions, they are suitable for use in removing all the heavy metal ions from industrial waste water for preventing pollution. These chelate resins, however, have a disadvantage in that since they are of low selectivity to specific metal ions, they cannot be employed in selectively separating, purifying and condensing the specific metal ions from the metal ion mixture in which various kinds of metal ions coexist, for example, in recovery of noble metal and the like.
As a method of separating or condensing uranium from an aqueous solution containing uranium, a solvent extraction method using amines is known. This procedure, however, is markedly disadvantageous from the practical standpoint since it requires a large amount of amines because of their low ability to complex with uranium.
Thus it has long been desired to develop novel materials capable of selectively and effectively capturing metal ions. Based on the discovery that 1,4,7,10-tetraazacyclotridecane has an excellent ability to capture metal ions, but that since said compound is water-soluble, it is difficult to separate and recover the metal ions captured from waste water and the like, it has now been found that introduction of alkyl groups containing 8 or more carbon atoms into the above 1,4,7,10-tetraazacyclotridecane decreases the solubility thereof in water while keeping its excellent capturing ability.